1. Field of the Invention
The present invention relates to a swallowable capsule camera for imaging of the gastro-intestinal (GI) tract. In particular, the present invention relates to a capsule camera that provides multiple video data stream to multiple receiving units for storage, from which a data stream may be derived for decoding and analysis.
2. Discussion of the Related Art
Devices for imaging body cavities or passages in vivo are known in the art and include endoscopes and autonomous encapsulated cameras. Endoscopes are flexible or rigid tubes that are passed into the body through a body orifice or through a surgical opening, typically into the esophagus via the mouth or into the colon via the rectum. An image is taken at the distal end using a lens and the image data is transmitted to the proximal end outside the body, either by a lens-relay system or by a coherent fiber-optic bundle. A conceptually similar instrument may record an image electronically at the distal end, for example using a CCD or CMOS array, and the image data is then transferred by electrical signal to the proximal end over a cable. The endoscope is an instrument that allows a physician control over its field of view and is a well-accepted diagnostic tool. However, endoscopes have a number of limitations, present risks to the patient, are invasive and are uncomfortable for the patient. The cost of these procedures restricts their application as routine health-screening tools.
Because of the difficulty in traversing a convoluted passage, endoscopes cannot reach most of the small intestine and special techniques and precautions, that add cost, are required to reach the entirety of the colon. Endoscopic risks include the possible perforation of the bodily organs traversed and complications arising from anesthesia. Moreover, a trade-off must be made between patient pain during the procedure and the health risks and post-procedural down time associated with anesthesia. Endoscopies are necessarily in-patient services that involve a significant amount of time from clinicians and thus are costly.
An alternative in vivo image sensor that addresses many of these problems is capsule endoscopy. In capsule endoscopy, a digital camera is housed in a swallowable capsule, along with a radio transmitter for transmitting image captured by the digital camera. The transmitted image data is received into a base-station receiver or transceiver for recordation in a data recorder outside the body. The capsule camera may also include a radio receiver for receiving instructions or other data from a base-station transmitter. Instead of radio-frequency transmission, lower-frequency electromagnetic signals may be used also. Power to the capsule may be supplied inductively from an external source or by a battery within the capsule.
An early example of a camera in a swallowable capsule is described in U.S. Pat. No. 5,604,531, issued to the Ministry of Defense, State of Israel. A number of patents assigned to Given Imaging (e.g., U.S. Pat. Nos. 6,709,387 and 6,428,469) describe such a system in greater detail. In each of these systems, the capsule camera includes a transmitter for sending the images captured to an external receiver. Other patents issued to Olympus Corporation describe a similar technology. For example, U.S. Pat. No. 4,278,077 discloses a capsule camera for the stomach, which includes film in the camera. U.S. Pat. No. 6,939,292 discloses a capsule with a memory and a transmitter.
An autonomous encapsulated camera with an internal battery has the advantage that the measurements may be made with the patient ambulatory, out of the hospital, and with only moderate restrictions of activity. The base station includes an antenna array that is placed surrounding the bodily region or regions of interest and this antenna array can be temporarily affixed to the skin or can be incorporated into a wearable vest. A data recorder is attached to a belt and includes a battery power supply and data storage medium for saving the images received by the antenna array and any other data transmitted. The stored data is subsequently uploaded onto a diagnostic computer system for analysis.
A typical procedure using such a capsule camera consists of an in-patient visit in the morning during which a clinician attaches the base station apparatus to the patient and the patient swallows the capsule. The system begins recording images just prior to swallowing and continues to record images of the GI tract until the battery completely discharges. Peristalsis propels the capsule through the GI tract. The rate of capsule passage through the GI tract depends on the degree of motility. Usually, the small intestine is traversed in 4 to 8 hours. After a prescribed period, the patient returns the data recorder to the clinician who then uploads the data onto a computer for subsequent viewing and analysis. The capsule is eliminated through the rectum and need not be recovered.
The capsule camera of the prior art allows the GI tract from the esophagus down to the end of the small intestine to be imaged in its entirety, although it is not optimized to detect anomalies in the stomach. Color photographic images are captured so that anomalies to be detected need only have small visually recognizable characteristics, not topography. The procedure is substantially pain-free and requires no anesthesia. The risk associated with the capsule passing through the body is minimal—certainly, the risk of perforation is much reduced relative to traditional endoscopy. The cost of the procedure is less than for traditional endoscopy due to the decreased use of clinician time and clinic facilities, and without using anesthesia.
In the prior art, a wireless capsule camera stores a single data stream.